Gas and liquid contact apparatus



y 3, 1967 H. K. NAJARIAN 3,321,191

GAS AND LIQUID CONTACT APPARATUS Original Filed July 7, 1961 7Sheets-Sheet 1 IM ENTOR HERA/VD K A/AJAR/AN y 3, 1967 H. K. NAJARIAN3,321,191

GAS AND LIQUID CONTACT APPARATUS Original Filed July 7, 1961 7SheetsSheet 2 INVENTOR HERA/VD A. NAJAR/A/V I ATTORNEYS May 23, 1967 H.K. NAJAWEAN GAS AND LIQUID CONTACT APPARATUS '7 Sheets-Sheet 5 OriginalFiled July '7, 1961 INVENTOR HERAND K, NAJARIAN ATTORNEY May 23, 1967 H.K. NAJARIAN GAS AND LIQUID CONTACT APPARATUS 7 Sheets-Sheet 4 OriginalFiled July 7.

INVENTOR HERAND K. NAJARIAN ATTORNEY y 23, 1967 H. K. NAJAREAN 3,321,191

GAS AND LIQUID CONTACT APPARATUS Original Filed July 7, 1961 7Sheets-Sheet 5 INVENTOR HERAND Kv NAJARIAN ATTORNEY May 23, 1967 H. K.NAJARIAN 3,321,191

GAS AND LIQUID CONTACT APPARATUS Original Filed July 7, 1961 7Sheets-Sheet 6 INVENTOR HERAND K. NAJARIAN A TTOR NE Y May 23, 1967 H.K. NAJARIAN GAS AND LIQUID CONTACT APPARATUS 7 Sheets-Sheet '2 OriginalFiled July '7, 1961 INVENTOR HERAND K. NAJARIAN BY 5M5 525% ATTORNEYUnited States Patent 3,321,191 GAS AND LIQUID CONTACT APPARATUS HerandK. Najarian, 1400 River Road, Beaver, Pa. 15909 Continuation ofapplication Ser. No. 122,578, July 7, 1961. This applicaticn Feb. 11,1966, Ser. No. 538,477 4 Claims. (Cl. 261-29) This is a continuation ofapplication Ser. No. 122,578, filed July 7, 1961, now abandoned.

This invention relates to a novel apparatus for providing intimatecontact between gases and liquid and particularly to an apparatus inwhich such contact is provided economically with low pressure drop andwith high and continually renewed contact surface areas between the gasand liquid phases.

One aspect of the invention pertains to a novel apparatus for separatingcontaminants from air or other gas, wherein the gas carryingcontaminants is scrubbed with a liquid scrubbing medium in theapparatus. Subsequently, a mixture of the captured contaminants andliquid scrubbing medium is withdrawn from the apparatus and relativelyclean gas is discharged from the apparatus. In this aspect the inventionis applicable to removal of various contaminants from air or othergases, such as, rock and mineral dusts, fly ash, acid, oil mists, dustsfrom mechanical grinders, lint, and the like, and comprises improvementsin gas cleaning apparatus designated in the arts variously asair-washers, scrubbers, gas cleaners, and wet dust collectors. In theapparatus of the invention, contaminants entrained in a gas areseparated from the gas by impinging the gas onto mobile surfaces of aliquid scrubbing medium contained in the apparatus, whereby thecontaminants separate from the gas by centrifugal force and areincorporated in the liquid scrubbing medium. Thereafter, a mixture ofcaptured contaminants and liquid scrubbing medium is withdrawn from theapparatus and the relatively clean gas is discharged from the apparatus.

Among typical examples of many useful applications of the improvedapparatus of the invention, may be mentioned:

Separating from air or other gases suspended rock dust, mineral dust,fly ash, dust from grinding operations, and the like, wherein a slurryof dusts and water withdrawn from the apparatus is allowed to settle insuitable reservoirs and clear reservoir overflow is returned to theapparatus and settled wet dust, if valuable as in the case of manymineral dusts, is recovered for reprocessing;

Separating minute liquid particles suspended in air or other gases, suchas acid mists, oil mists, paint spray, and the like, and removing saidmists as a suspension or solution in the liquid scrubbing medium.

The most effective means of separating suspended contaminants from afluid mass is to subject the fluid to centrifuging action. This appliesto gases as well as to liquids. The most effective way of centrifuginggases is to impinge a stream of the gas against surfaces normal or at asteep angle to the direction of the flow of the gas and, thus, obtain anabrupt turn in the direction of gas flow. Heavier particles tend toremain in the direction of flow and, thus, are thrown out of the gasstream against said surface. When the surface on which the gas is causedto impinge is a liquid surface, then these heavier particles ofcontaminants are forced into the body of the liquid scrubbing medium.

Secondly, the surfaces on which the gas impinges in its passage throughthe scrubbing apparatus should be unbroken liquid surfaces and shouldremain substantially unbroken in the zone of impingement. When a streamof gas flowing substantially horizontally impinges on a thin sheet ofliquid scrubbing medium, falling free in the gas 3,321,191 Patented May23, 1967 stream, the velocity of the stream of gas will tend to break upthe thin sheet of liquid scrubbing medium into a shower of liquiddroplets. There will be little, it any, change in the direction of thegas stream and, consequently, no centrifuging of the heaviercontaminants suspended in the gas stream and insignificant separation ofthe contaminants from the gas stream. However, if the sheet of liquidscrubbing medium is made to flow over the surface of a near vertical orsteep solid wall, such as a sheet of steel plate and the gas streamimpinged against the sheet of flowing liquid scrubbing medium, then theimpingement will cause the stream of gas to change direction abruptlycausing the contaminants to be thrown against the flowing stream ofliquid scrubbing medium and carried away by the liquid scrubbing medium.In the scrubbing apparatus of the invention, the gas stream carrying thesuspended contaminants is caused to impinge vertically or at a steepangle initially on surface of a deep pool of the liquid scrubbing mediumand, subsequently, impinged on inclined surfaces of baffled channels ofnovel design being washed by unbroken sheets of liquid scrubbing mediumflowing continuously so that the gas stream throughout its passagethrough the scrubbing apparatus is subjected to repeated impingementsagainst such sheets of liquid scrubbing medium which provide idealimpingement surfaces and which automatically wash the contaminants awayfrom the impingement surfaces and prevent build up of accretions.

An important feature of the invention which contributes substantially tothe high degree of efficiency of elimination of contaminants from a gasbeing processed through the apparatus of the invention is the novelmethod whereby the entire stream of dirty gas to be cleaned firstimpinges in its entirety and preferably vertically downwards onto asurface of the main body of liquid scrubbing medium held in theapparatus. Thereafter, said main gas stream is subdivided intosubstreams of much smaller cross-sectional area and the subdividedportions of the gas stream are passed severally upwardly through bathedinclined channels, impinging during said upward passage repeatedly ontosheets of liquid scrubbing medium covering the internal surfaces of saidbaflied tubes and moving concurrently with said portions of the gasstream. The contaminants thrown out of the gas stream by repeatedimpingement are incorporated in the liquid scrubbing medium flowingthrough the several bafiied tubes and carried into the main body ofliquid scrubbing medium.

The subdivision of the main stream of gas into many incremental streamsis very important. When a stream of gas of a large cross-sectional areais caused to impinge onto the surface of a pool of liquid scrubbingmedium, vertically or at a steep angle, the gas stream makes a sharpturn at the surface of the liquid. Depending partly on the velocity ofimpingement and cross-sectional area of the gas stream, only the largestand heaviest particles of contaminants reach the surface of the liquidscrubbing medium and are plunged into the body of the liquid. Smallerand lighter particles, because of the relatively smaller centrifugalforce imposed on them and also the greater distance from interiorregions of the gas stream to the surface of the liquid scrubbing mediumremain in the gas stream. If the gas stream, following the initialimpingement and partial cleaning, is subdivided into numerous substreamsof much smaller cross-sectional areas and is repeatedly impinged onsurfaces of the liquid scrubbing medium farther along with theapparatus, large proportions of the remaining smaller and lighterparticles of contaminants will be recovered from the subdivided streamof gas and incorporated into the liquid scrubbing medium. The baflledinclined tubes are so designed that the number of additionalimpingements received by the gas as it travels through the baffledinclined tubes is determined in accordance with the amount ofcontaminants remaining in the gas stream after the initial impingement,thoroughness of elimination of contaminants desired, and other factors.

A further important feature of the invention is that the stream of dirtygas passing through the apparatus comes in contact only with internalsurfaces of the apparatus that are continually being washed withsubstantially unbroken sheets of liquid scrubbing medium until clean airor gas passes through the entire impingement and cleaning zone withinthe apparatus. Thus, accumulations of solid contaminants on damp,inactive, and unwashed surfaces within the apparatus through contactwith dirty incoming gas are avoided and the necessity for periodiccleaning of the apparatus is minimized.

One of the problems in connection with operation of all types of air andgas cleaning apparatus is the disposal of the captured contaminants. Theapparatus of the invention provides the simplest of means for disposalof such contaminants. Provision is made for accumulation of thecontaminants within the apparatus as a suspension or solution of thecontaminants in the liquid scrubbing medium. Periodically or, ifdesirable, continuously, the suspension or solution of contaminants ispumped out of the apparatus. If the contaminant has economic value, thenthe mixture of contaminant and scrubber liquor is processed by any oneof well known recovery methods for recovery of the contaminant in a formsuitable for further processing or sale.

In another aspect of the invention, apparatus may be used for efiicientand economical aeration of various liquids such as waste liquors fromtanneries, abattoirs, paper mills, and the like, and in particular, rawsewage. The term aeration will be used herein to designate the processwhereby components of a gas soluble in or miscible with a liquid aretransferred from the gas into the body of the liquid medium and aredissolved or retained therein.

Various methods are disclosed in the prior art for aerating liquids withgases. A most commonly used method is to force the :gas under pressurethrough orifices at or near the bottom of a body of liquid and let thegas bubbles go upwardly to the surface of the liquid. Since the airbubbles come in contact with the liquid only on the spherical gas-liquidinterface, a relatively large volume of gas in the interior of thebubble does not come in contact with the liquid and therefore aerationis slow and inefiicient. To increase the efficiency of the above methodof aeration, mechanical diffusors or spargers are sometimes used tosubdivide the larger bubbles into smaller ones. However, smaller airorifices are subject to clogging by accretions necessitating frequentstopping of operation, removing and cleaning 'of the orifices.

Another method used sometimes is to agitate the body of liquid at thesurface to cause circulation with mechanically rotated blades. Thismethod also is inefiicient and slow due to the fact that the liquidcontacts the gas on the surface with no gas velocity to causeimpingement effect and also the layer of gas immediately above theliquid soon gets depleted of the component of the gas soluble ormiscible with the liquid, resulting in lowering the rate of aeration.

In the present invention, thin layers of fresh undepleted gas areimpinged against surfaces of liquid repeatedly as the gas and liquidpass at high velocity through many impingement zones in the apparatus,thus saturating part of the liquid continuously. Thereafter, thesaturated portion of the liquid is caused to flow into the main body ofliquid deficient in gas, thus agitating the body of liquid and diffusingthe gas uniformly into the entire body of the liquid, as hereinaftermore fully described. The principal object of this aspect of theinvention is to increase the rate of aeration above usual rates ofaeration obtainable by prior art methods so as to reduce the time ofretention of the liquid within the apparatus for completion of chemicalreactions promoted by the aeration. Another object of the invention isto minimize the maintenance of the apparatus in the initial gas-liquidcontact zones normally subject to cumulative build-up of accretions andresultant clogging of gas passages by having such contact zones easilyaccessible without disturbing the continuity of operation of theapparatus. A further object of the invention is to provide apparatus inwhich the several baffled inclined channel units are interchangeable andeasily removable and replaceable without interrupting the operation,thus making maintenance simple and inexpensive.

In processes designed for stabilization of various waste productsdissolved or suspended in water such as raw sewage, and industrialliquid wastes, usually the first step is to aerate the liquor in orderto oxidize and stabilize quickly the putrifiable odor producing organicmatter in solution in the liquor. In a second step the undissolvedsuspended waste matter is settled as sludge and the main portion ofliquor containing the stabilized waste matter in solutionis allowed tooverflow for disposal. The settled sludge is then processed further tooxidize and solubilize all organic matter until a residue comprisingchiefly of inorganic insoluble matter is left for disposal at intervals.

The sludge comprising mainly of solid or colloidal organic waste matteris further treated to \burn the organic compounds to make them solubleso that they can be disposed of in overflow as stable compounds. Onemethod of treating sludge is by activation. In this method, the sludgeis retained in settling basins and sometimes heated to promoteactivation by bacterial growth producing the needed oxygen to oxidizethe organic matter.

In another method, the sludge is oxidized under high pressure and athigh temperature in autoclaves for acceler-ated oxidation.

In another method, sludge and often raw sewage are retained for longperiods, normally several months, in shallow lagoons where oxidation oforganic waste matter progresses slowly through photosynthesis, algaegrowth and bacterial action.

Final products of above treatment methods for domestic and industrialorganic wastes are free of odor producing, putrifiable compounds and theliquors are disposed of without producing nuisance.

The apparatus of the invention may be used not only in preliminaryaeration of waste liquors to oxidize the waste matter in solution, butby returning the settled sludge to mix with raw liquor feed preferablyat intervals, complete stabilization can be achieved in simpleinexpensive apparatus.

The invention will be more particularly described with reference to theaccompanying drawings in which:

FIG. 1 is a diametrical vertical section through a cylindrical gasscrubber embodying the principles of the inventron;

FIG. 2 is a horizontal section on line 2-2 of FIG. 1;

FIG. 3 is a detail in partial section on line 33 of FIG. 2, showing theconstant level overflow arrangement;

, FIG. 4 is a longitudinal vertical section of an aerator embodying theprinciples of the invention;

FIG. .5- is a plan view of the aerator of FIG. 4;

FIG. 6 is a transverse vertical section on line 6-6 of FIG. 4;

FIG. 7 is a transverse vertical section of a modified form of theaerator of FIG. 4;

FIG. 8 is an enlarged sectional view of the removable andinterchangeable baffled inclined channel member of the invention asmounted in the aerator of FIGS. 4-7;

FIG. 9 is a view of the channel member of FIG. 8 showing the outlet endthereof; and

FIG. 10 is a top view of the channel member of FIG. 8.

In FIGS. 1-3 ofthe drawings, 10 is a cylindrical tank, preferably ofsteel, having a conical bottom sump section 11. 12 is a truncatedconcentrically positioned cone within tank 10, spaced above the bottomcone of the tank, and having an opening at the bottom into sump of tank10. Within the upper part of tank and projecting upwardly from the lowerpart of the inner cone 12, is a cylindrical wall 13 dividing the spacewithin the main tank into an inner gas inlet chamber 14, and an annulargas exhaust chamber 15. From the periphery of inner cylindrical wall 13,and spaced above the bottom thereof, baffled channels 16 projectradially into the outer annular gas outlet chamber 15. Baffled tubes 16areinclined upwardly from the gas inlet chamber 14 into gas outletchamber 15, preferably at a 20 30 angle from the horizontal. Bafiies 17project from floor and roof of the inclined tubes 16. The number. ofbaffles 17, the distances between baflles andthe height thereof areselected to meet the requirements of nature of the gasto be cleaned, thecontaminants found in the gas, the concentration of said contaminants inthe gas and other factors. The length of the inclined baffled tubeslikewise is varied in accordance with burden imposed by various gases,such as, loading of contaminant, wetting qualities of soliddustor fumecontained in gas. Easily wet fumes and dust and smaller percentages ofcontaminants .require shorter tubes than fumes and dust diflicult towetand when the gas is heavily loaded. Directly above the lower openings ofradially disposed bafiled inclined tubes 16 is a trough 18 adapted toreceive and hold quantity of liquid scrubbing medium. Annular trough 18is. formed by the wall of cylindrical wall 13 and an inclined member 19projecting from directly above the top of the lower end of the inclinedbafl led tubes into the gas inlet chamber 14. Liquid scrubbing mediumfrom trough 1,8 overflows over the upper edge of inclined member 19 intothe main body of liquid scrubbing medium 20 held in the lower portion ofmain tank 10. A baflle 21 serves to equalize overflowof liquid scrubbingmedium over the edge of trough member 19. The bottom portion ofannular'gas exhaust chamber communicates with conical bottom of maintank 10 below the level of body of liquid scrubbing medium throughopenings 30,

at bottom. of wall .13.. Air or other gas containing contaminants entersthe gas inlet chamber 14 through vert cally disposed duct 22 andimpinges initially onto the mam body of. liquid scrubbing medium 20 andmushrooms out in all directions as indicated, by arrows, and thereafterthe stream of gas is subdivided into substreams as the gas passesupwardly through the baffled inclined tubes 16 into the gas exhaustchamber 15 above theupper body of liquid scrubbing medium, As thestreamof gas mushrooms out towards the lower inlet openings of the baflledinclined tubes the velocity of the gas pushes the sheet of M liquidscrubbing medium overflowing the trough 18 onto the undersurface ofinclined trough member 19 andinto the. .bafl led inclined tubes, wherethe sheet of liquid scrubbing medium is transported, upward along theroof of said tubes and overthe bafiles therein by the stream of 1 gasand as it is propelled by the gas stream along the tortuous pathshownbyarrows within the inclined channels, the liquid forms concavesurfaces 32 between the baflies against which concave surfaces of liquidscrubbing medium stream of gas impinges, thenurnber of impingementsdependingon number of bafiles. Furthermore, a continuous sheet of liquidscrubbing medium comprising portions of the main body of liquidscrubbing medium 20 is propelled upwardly alongthe floor of said baffledinclined l tubes by said upward passage of the stream of gas. The

stream of liquid, scrubbing medium, as it passes over the transversebaffles along the bottom of inclined tubes and .deviated by gas stream,forms concave surfaces 33 onto which gas stream ,impinges alternate toconcave surfaces 32 along the roof ofinclined tubes a p e ,As, thesubdivided streams of gas travel upwardly through baffled inclined tubes16 along the tortuous path shown by arrows, the change of directionforced on the stream of gas by transverse bafiles 17, causes the streamt t 6 t of gas to impinge alternately on curved surfaces 32 and 33 ofthe sheets of liquid scrubbing medium. With each impingement additionalcontaminants are separated from the gas stream by centrifugal action andthe contaminants are carried off by the liquid scrubbing medium passingupwardly through the tubes, which is discharged from the upper end ofthe tubes into the body of scrubbing liquid in the annular dischargechamber. As long as the apparatus is in operation, liquid scrubbingmedium flowing into the upper body of liquid scrubbing medium returnsdownwardly through wedge-shaped openings between tubes, along the bottomof upper cone 12 as shown by arrows and through openings 30 at bottom ofcircular partition 13 down into the lower cone. Here the contaminantscongregate as a mixture or slurry of the contaminants with liquidscrubbing medium, and may be withdrawn, as for instance, by a commonslurry pump 36 and transported to settling pond for recovery ofcontaminant if said contaminant is valuable. Otherwise, it may be pumpedto a disposal area. The main part of the liquid scrubbing mediumreturning from exhaust chamber 15 to lower settling cone 11, after thecontaminants have separated by settling, becomes relatively .free ofcontaminants, a portion of the clear liquid scrubbing medium rises tothesurface of main body of liquid scrubbing medium 2t) and the remainderoverflows through overflow openings 26 into launder25 and from therepumped, by pump 24, through pipes 27 into trough 18 in gas entrancechamber 14.

, Referring particularly to FIG. 3, a cylindrical vessel 37 is connectedto annular exhaust chamber at the level of the liquid scrubbing mediumthrough box 38 and passage 39. ,A small diameter pipe 40 projectsupwardly to a small distance below the level of liquid scrubbing mediumand is provided with an adjustable coupling 41 at upper end. Pipe 40projects downwardly and is provided with an inverted syphon to permitretention of a body of liquid as a seal against suction in exhaustchamber 15, a small diameter vent 42 equalizes pressure in 3 7 andexhaust chamber 15. When the level in 15 rises due to excess make-upliquid, the liquid overflows coupling 41 and passes through pipe 40 intowaste launder 43.

In operation the sump is initially filled with liquid wash medium to alevel at which the lower ends of the inclined baifled passages 16 arewholly or nearly submerged. The gas flow and the wash liquid pump may bestarted simultaneously or in succession. Typically, the flow of the gasand liquid wash medium upwardly through the inclined passages requires apressure differential between the gas inlet chamber and the gas outletchamber of from four to eight inches of water. During operation, becauseof the pressure differential between the inlet and outlet chamberscaused for example by a conventional air compressor as shown at 6! inFIGURE 5, the level of liquid in the outlet chamber stands higher thanthe level in the inlet chamber, as indicated in FIG. 1 of the drawing,and as liquid wash medium is carried from the sump into the outletchamber through the outlet passages, an equivalent amount of liquid washmedium laden with contaminants flows downward from the outlet chamberbetween the passages into the lower portion of the sump.

The aerator of FIGS. 4-6 comprises a vessel 51 in its preferred form along relatively narrow trough made of steel or concrete and adapted tohold body of liquid and having an opening 52 at one end for admission ofraw sewage or industrial waste liquor and a second opening 53 fordischarge of aerated sewage or liquor, one or more gas inlet chambers 54within vessel51 spaced from Walls and bottoms thereof to allow freecirculation of liquid and having gas inlet openings 55 to supply gasunder pressure to said chambers and baffled gas outlet passages 56inclined upwardly from the gas inlet chamber to vessel 51.

Except for small capacity installations, it is preferable to have anumber of gas inlet chambers 54 positioned equidistant within the vessel51 to permit regulation and equalization of air pressure within theseveral gas inlet chambers, the number of the chambers depending on thetotal length of the aerator and aerating capacity desired.

Since aeration proper constitutes normally the initial step in processesfor complete stabilization of raw sewage and industrial waste liquors,it is desirable to provide a settling basin 57 as auxiliary to theaerator, so that the aerated product is allowed to run into the settlingbasin having an overflow 58 common to both aerator and the settlingbasin to permit regulation of the liquid level in the aerator as well asthe settling basin. Aerated sewage or liquor is allowed to pass throughdischarge opening 53 of the aerator into the lower part of the settlingbasin 57 and the level of liquid in settler as well as aerator vessel 1is maintained by regulating overflow opening 58. The

sludge accumulating in the lower portion of settling basin 57 may beremoved by pump means 59 and processed further in accordance withvarious methods referred to above or it may be transferred and mixedwith incoming raw sewage or waste liquor for repeated treatment in theaerator.

An air compressor 60 is provided to furnish gas under pressure to theseveral gas inlet chambers through gas header 61, and header branches62, the amount of gas being regulatable by dampers 63. Raw sewage orliquors enter the aerator through supply pipe 64 and feed compartment 65and return sludge is transported through pipe The bafiled inclinedchannels 56 projecting upwardly from the gas inlet chamber 54 into theouter vessel 51 are removable and interchangeable so that they can beeasily removed during operation for inspection or cleaning if necessary.Furthermore, when a channel unit with, for example, small number ofbaflies does not prove adequate, others with a larger number of bafliesor larger openings and different baflle heights may be substitutedwithout disturbing the operation of the aerator. One form of removablebaffled inclined channel is shown in FIGS. 8-10 wherein gas inletchamber 54 has an opening 67 into outside vessel 51 and bracket 68permanently attache-d to the outside wall of the gas inlet chamberadjacent opening 67. The removable baffled channel unit comprises anoutside shell 70, projecting baflies 71 inside said shell and a flange72 at one end whereby the channel unit may be locked in place againstthe wall of the gas inlet chamber 51 by means of wedges 73 having holesat the upper end to permit easy removal and replacement.

A modification of the gas supply to the aerator is shown in FIG. 7 inwhich identical elements are numbered as in FIGS. 4-6. When sewage andindustrial waste liquors contain large proportions of solid material insuspension which may settle to the bottom of aerator, it may becomenecessary to agitate the bottom region of the aerator vessel 51 morevigorous-1y than is provided by the circulation induced by liquidpropelled from the gas inlet chamber to the outside vessel in order tokeep the solid and colloidal matter from settling and accumulating inthe aerator. Therefore, air pipes 74 are provided projecting downwardlyfrom air header 61 into the gas inlet chambers and having an opening atend thereof below the surface of the liquid, preferably near the bottomof vessel 51. Valves 75 regulate the air flow through above pipes 74.Air discharged from bottom of pipes 74 bubbles through the liquid up toupper portion of gas inlet chamber 54 and passes through the inclinedbaflied passages as in the apparatus of FIGS. 4-6 agitating the bottomof the trough.

Operation of the aerator form of the apparatus of the invention is asfollows:

The liquid holding tank 51 of the aerator is filled with the liquid tobe aerated to a'level determined by the elevation of the lower openingsof the baffled inclined passages 56. The lower openings of thesepassages should be Completely submerged when the liquid is at rest. Whengas compressor 60 is started and pressure builds up in the several gasinlet chambers the level of liquid in gas inlet chamber will go downuntil the lower ends of the inclined passages are exposed and gas startspassing up the inclined passages. The quantity of gas supplied each unitof gas inlet chamber is regulated by dampers 63 so as to maintain a highvelocity of gas flow through the inclined passages, normally 20004000feet per minute, to cause strong impingement of gas on liquid and forcethe gas into the liquid against the surface tension of the liquid "andalso to have driving power to transport a quantity of liquid upwardlyinto the upper portion of the liquid body at the outer region of theholding tank. Thus, the liquid is saturated by gas during passagethrough inclined channels and saturated liquid collects in the upperportion of the holding tank and then flows under the head created by thetransport of liquid through the inclined channels towards the bottom ofthe holding tank, diffusing the gas into the gas-depleted portion of theliquid and in addition inducing a circulation of the entire mass ofliquid crosswise of the liquid holding tank as the mass of liquid slowlymoves lengthwise from the feed end to the discharge end of the aerator.The gas diflused into the body of liquid at lower portion of the holdingtank is consumed in the chemical reactions occurring as part of theaeration process and the gas depleted liquid is again passed through thebaflled inclined passages to start another cycle of saturation anddiffusion. As gas and liquid are ejected from the upper opening of the'bafiied inclined passages, the liquid turns downward and the gas passesout of the liquid as shown by the arrows in FIG. 6. The crosswisecirculation within the body of liquid in the holding tank serves toaerate uniformly the entire body of liquid and keeps it aerated until itis discharged from the aerator. The concentration of organic wastematter in the waste liquor or sewage and its susceptibility to chemicalchange by aeration determine the retention time of the liquid in theaerator and is usually resolved by testing.

When conditions require, the aerator apparatus may be operated bysuction applied over the liquid in the holding tank, using the gas inletopenings in the gas inlet chamber for admission of gas into theapparatus.

It will be seen that in its various aspects the apparatus of theinvention generally comprises a liquid holding vessel having suitableliquid supply and outlet means, an inverted open-bottomed gas chamber inthe upper portion of the liquid holding vessel, the wall-s of the gaschamher being spaced at least in part from the walls of the liquidholding vessel to provide passage for liquid therebetween, meansproviding baffled passages inclined upwardly from the upper portion ofthe gas chamber into the upper portion of the liquid holding vessel, andmeans for supplying a gas to the gas chamber under a pressure greaterthan the pressure in the upper portion of the liquid holding vessel. Thedetails of form and arrangement shown in the drawings are merelyillustrative of the principles of the invention and variations embodyingthese principles within the scope of the claims will be obvious from theforegoing description of the principles and illustrative embodiments ofthe invention.

What is claimed is:

1. A gas scrubber comprising a casing having a gas inlet and a gasoutlet in the upper portion thereof and providing a liquid-holding sumpin the bottom portion thereof, partition means dividing the upperportion of the casing into an inlet chamber including the gas inlet andan outlet chamber including the gas outlet and extending downward intothe sump and spaced apart from the bottom thereof, a plurality ofpassages through said partition means inclined upwardly from said gasinlet chamber into the gas outlet chamber, a plurality of baflies ineach of said passages to thereby define hurdles for gas and liquidflowing therethrough, said baflies extending inwardly of said passagesand positioned crosswise of the flow path through said passages, a bodyof liquid wash medium in said sump, gas propelling means for maintainingpressure differential between said gas inlet and gas outlet chambers tocause the level of said sump liquid in the gas outlet chamber to stay adistance above the baflled, inclined passages and simultaneously to keepthe level of the sump liquid at the bottom of the gas inlet chamberbelow the gas passages from the gas inlet chamber into the lower ends ofsaid inclined, baflled passages, means for supplying liquid wash meduimto said sump, and liquid overflow means to maintain said level of sumpliquid in the gas outlet chamber, the liquid in said outlet chamberincluding liquid carried from said sump up through said baflledpassages.

2. The scrubber of claim 1, wherein the outlet ends of said plurality ofbafiled passages are angularly separated to thereby define gapstherebetween, means communicating said gaps with the liquid in the sump,whereby liquid carried upwardly in said plurality of bafiled passagesspills over into said gaps and down into said sump.

3. Gas and liquid contact apparatus comprising a liquid-holding vessel,a gas inlet, a gas outlet, means providing an inverted open-bottomed gaschamber in the upper portion of said vessel, the Walls of said gaschamber being spaced at least in part from the walls of the vessel toprovide passage for liquid therebetween, means providing passagesinclined upwardly from the upper portion of the gas chamber into theupper portion of the vessel, a plurality of baflles in each of saidpassages to thereby define hurdles for gas and liquid flowing therethrough, said baflles extending inwardly of said passages and positionedcrosswise of the flow path through said passages, means for maintaininga pressure difierential between said gas inlet and gas outlet to causethe level of a liquid in the liquid holding vessel to stay a distanceabove the bafiled, inclined passages, means for supplying liquid to saidvessel and means for supplying a gas under pressure to the top portionof the gas chamber including means for supplying gas to the gas chamberbelow the surface of the liquid therein.

4. Gas and liquid contact apparatus comprising a liquid-holding vessel,means providing an inverted, openbottomed gas chamber in the upperportion of said vessel, the walls of said gas chamber being spaced atleast in part from the walls of the vessel to provide a continuouspassage for liquid therebetween, a plurality of baflled passagesinclined upwardly from the upper portion of the gas chamber into theupper portion of the vessel, each of said passages including a pluralityof bafiles therein to thereby define hurdles for gas and liquid flowingtherethrough, said baflles extending inwardly of said passages andpositioned crosswise of the flow path through said passages, saidplurality of baflled passages being angularly separated from each otherto thereby define gaps therebetween, means communicating said gaps withthe lower portion of said liquid-holding vessel, whereby liquid carriedupwardly in said plurality of baffled passages may spill down into thebottom portion of said liquid-holding vessel.

References Cited by the Examiner UNITED STATES PATENTS 2,360,229 10/1944Holmes 261-121 2,585,659 2/1952 Kilpatrick -85 X 2,883,170 4/1959Trittipoe 261-112 FOREIGN PATENTS 504,843 12/ 1954 Italy.

HARRY B. THORNTON, Primary Examiner. RONALD R. WEAVER, Examiner.

3. GAS AND LIQUID CONTACT APPARATUS COMPRISING A LIQUID-HOLDING VESSEL, A GAS INLET, A GAS OUTLET, MEANS PROVIDING AN INVERTED OPEN-BOTTOMED GAS CHAMBER IN THE UPPER PORTION OF SAID VESSEL, THE WALLS OF SAID GAS CHAMBER BEING SPACED AT LEAST IN PART FROM THE WALLS OF THE VESSEL TO PROVIDE PASSAGE FOR LIQUID THEREBETWEEN, MEANS PROVIDING PASSAGES INCLINED UPWARDLY FROM THE UPPER PORTION OF THE GAS CHAMBER INTO THE UPPER PORTION OF THE VESSEL, A PLURALITY OF BAFFLES IN EACH OF SAID PASSAGES TO THEREBY DEFINE HURDLES FOR GAS AND LIQUID FLOWING THERETHROUGH, SAID BAFFLES EXTENDING INWARDLY OF SAID PASSAGES AND POSITIONED CROSSWISE OF THE FLOW PATH THROUGH SAID PASSAGES, MEANS FOR MAINTAINING A PRESSURE DIFFERENTIAL BETWEEN SAID GAS INLET AND GAS OUTLET TO CAUSE THE LEVEL OF A LIQUID IN THE LIQUID HOLDING VESSEL TO STAY A DISTANCE ABOVE THE BAFFLED, INCLINED PASSAGES, MEANS FOR SUPPLYING LIQUID TO SAID VESSEL AND MEANS FOR SUPPLYING A GAS UNDER PRESSURE TO THE TOP PORTION OF THE GAS CHAMBER INCLUDING MEANS FOR SUPPLYING GAS TO THE GAS CHAMBER BELOW THE SURFACE OF THE LIQUID THEREIN. 